The rocker arm pivot is supplied as a casting, but if used for the reversed valve layout does not put the pivot centrally in the rocker arm. I spent a while studying the casting and working out a cunning plan that would still allow the casting to be used but shift the pivot point nearer to the valve.

The first job was to just take enough off the casting to remove the draft angles on the two edges that will mount to the head and also set these at 90 degrees to each other so I had a datum to work with.

I also skimmed the draft off around the pivot so that I could get a decent grip of the casting to bring it to thickness.

The casting was offered up to the head and a line scribed to mark where the mating area stopped and a ball nosed cutter used to tidy up that area to the line.

Then it was out with the Sharpies to refine the shape, I left as much material as possible on the face that was machined earlier which moved the pivot point further from the head so the green pen marks where the opposite edge needs the excess material removed and the red shows where the screws will go to mount it to the head.

Drilling and reaming 3mm for the pivot pin.

Then rounding around the pin hole on the rotary table.

Last bit of machining for now was the slot for the rocker arm.

Finally the bracket in place, I have removed a bit of material from the head so it matches the depth of the bracket. After test running it will be bonded on and filleted with JB Weld so that it looks like an integral part of the head casting; edges will also be eased to make it look like a casting. There is still work to be done where the push rod goes but more of that later.

PART ONE  TWO  THREE  FOUR  FIVE  SIX  SEVEN  EIGHT  NINE